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ILF Chemistry Presentation
Transcript of ILF Chemistry Presentation
-Pure Caffeine powder -Funnel
-Balance -Stirring stick
-Weighing boat -100ml volumetric flask
-Scoop -Rubber stopper
-Distilled Water -Waste and working beakers Samples are put through the filter and injected into the machine The solvent is put through a high pressure pump. This is called the mobile phase. The sample is carried by the solvent into a column containing very polar, solid particles. This is called the stationary phase. Because the column particles are so polar, it takes some time for the mobile phase to pass through. Every chemical takes a differnt amount of time. As the mobile phase exits the stationary phase, it passes through a detector then into a waste container. The detector detects when the caffeine passed through, and how much was there. This data is sent to a computer that records it and creates a Chromatogram. Chromatogram Chromatograms are used to show: when, and how much of a compound passed through the detector. The amount is on the Y axis and time is on the X axis. Results: References: Henry, S. (1999, July 21). Health benefits of caffeine. Retrieved from http://www.fitwise.com/Benefits_Caffeine.asp Johnson, W. (2008). Coffee-health risks drinking too much. Westminster College SIM HPLC 1, Determination of Caffeine in Beverages Xiang. Liu. Lee, Y. Y. M,L. (2005, November). Ultrahigh pressure liquid chromatography using elevated temperature. Safety gear that was worn at all times:
- Nitrile gloves Safety precautions:
-Shorts and open toed shoes were not worn
- No shenanigans and/or tomfoolery
-Proper training and safety information was provided Caffeine analysis:
-6 samples and a caffeine standard
-3 beakers, stock, working, waste.
- 10ml syringe with a 0.5 micron filter
-1ml syringe with a 0.2 micron filter
-HPLC machine The beverage samples that were collected were tested for caffeine levels against our caffeine standard with a concentration of 0.36 mg/ml Conclusion Possible Sources of Error Unfortunately, even when working with very high tech equipment and using the utmost precision and accuracy when performing tests, there are always going to be several factors that will possibly have an effect on the resulting data. These are some of them: 1.We may have not used the same amount of water for each sample due to the precision of the K-cup machine. When the samples, there was a preset on the machine for an 8 oz serving and the machine may have used too much water or too little. This would have affected our results by causing the samples to have more or less caffeine then they should have had preparing in their 8 oz serving. 2.We only did one run of each sample. This caused us to calculate the caffeine concentration of only one cup of the sample so it could vary between different cups. If we had done numerous runs, we could have averaged out the caffeine concentration in the samples. 3.While running our samples at UNB with Dr. Tong, we were subject to measuring the area under the curve. The program that was used required us to guess exactly where the arch began and ended and this could have slightly skewed the final data. 4.We created our own standard for the test and because we are not the most experienced chemists, the amount of caffeine could have been off. 5.Because this was the first time that any of us had performed these tests, simple mistakes that would not be made by more experienced individuals could have occurred and changed the resulting data. Some examples of these discrepancies include procedures such as the operation of the instrumentation and mechanical inputs to the machines. In Summary After referring to our results we have determined that Bigelow’s Green Tea and Timothy’s 5 assorted coffees and teas have an average percent error of 31,26%. Once this value was recorded, we reviewed our sources of error and assessed that their estimated caffeine values could possibly be inaccurate. If we were to validate our hypothesis, we would have to perform multiple tests on a larger sample size. From this project our group was educated on the HPLC process, how to prepare samples and standards at a higher level, and have all gained a passion for analytical chemistry as a whole. so, standards (ben), hplc (eric), error (bene) and conclusions (craig/eric)? We created a caffeine standard with a concentration of 0.36 mg/ml. The standard was used as a known concentration value so we could determine the amount of caffeine in our K-Cup samples. Final Results